I have been dealing with a small surface finish issue with my X3 for sometime now. just tonight I checked the run out of the spindle and as best I could tell it's within .0005", But I did notice something else, If I put a dial indicator on the side of the head (with the base stuck to the table) grab the drawbar from the top and push and pull on it I easily get +- .005 or .010 TIR. If I really pull and push on it I can get almost .020 TIR! I then spent a hour or so working with the Z axis Gib, even totaly locking it down and get the same amount of TIR. Is this normal for this size of a machine? If anyone out there has an X3 and would be willing to try the same, I would be curious to hear what kind of deflection you get.
Thanks!
Bob

Hi Bob,

I just bought myself a X-3 Super a few days ago and this is what I measured when it came of the crate:

The runout of the spindle is .0003"

As for pushing and pulling the drawbar, I get:
Pushing + .002"
Pulling - .002"

The head was in it's highest position. The mill itself wasnot mounted on a surface.
It is likely that I will get different results when I mount it to a table, that would allow my to push/pull harder without tipping it over.

Pat

Is everything bolted down tightly?

On my x2 I get more than .002 I know that. One thing you want to look at is if the mill is trammed, put an indicator and swipe it in circles around the table and see what it does, just .0005 in a 3" radius will cause potential messyness.

I have seen some bases made for the x2 that have some rods or braces holding the column up tight which would help.

Jon

Ok,
This is what I have found, The column on the X3 is basically a U-shaped section of cast iron. If I push on the column directly in the x or w direction I only get a minimal amount of deflection, however, If I grab the column with 2 hands and try to twist it I get a large amount of deflection. So how can I make the column more ridgid to a twisting motion? The head being "relativily" far from the column acts as a moment arm and can easily *twist* the column.
Any Ideas On how to make it more ridgid?
Thanks!
Bob

Hi Bob;

Not to pop any ballons here but to get a stiffer machine you would need to step up to something like a Bridgeport clone. There may be other alternatives besides that, but a stiff machine will require mass and good design.

As to your issue first described in this thread, it is hard for me to grasp what you are describing. One thing to consider is attaching the indicator to the head in such a manner that you eliminate all other mechanical joints and see what you get. There are a few things to be concerned with when checking out a spindle.

First is radial run out followed by axial run out. Associated with the axial runout is the amount of deflection you get on axis when applying pressure to the spindle.

In essence if you can move the spindle up and down you have a set of poorly adjusted bearings or other mechanical problems leading to little preload. Lack of preload could also result in you seeing lateral deflection of the spindle. You could also have a tolerance problem leading to lateral deflection.

In any event if you have concerns about the spindle (or any element of a machine for that matter) you need to isolate your measurements to the area you thing the problem is. That is why I suggested repositioning the indicator. My gut feeling is that the bearings might be loose, followed closely by errors due to measurement techniques.

Dave